In general, with the increase in demand for exchanges of information via wireless communications, needs for communications systems using microwaves are increasing. Devices used in a wireless communications field tend to have a smaller size and a higher capacity. Furthermore, working frequencies thereof are changed to a high frequency band, and thus the GHz frequency band is being utilized.
Currently, a dielectric material is widely used in a resonator, which is a principal device constituting a part of such a communications system used in such a high frequency band, employing microwaves with a range of 300 MHz to 300 GHz.
FIG. 1 is a perspective view showing a conventional resonant device using a dielectric resonator 14. The dielectric resonator 14 is attached to an upper surface of a dielectric layer 10, and a microstrip line 12 is formed to be spaced apart from the dielectric resonator 14.
The conventional dielectric resonant device of FIG. 1 may be applied to circuits such as a multilayer circuit, an MMIC (monolithic microwave integrated circuit) and a filter to be used in a wireless communication system. However, the conventional dielectric resonant device has a problem in that it is difficult to fabricate the dielectric resonant device to have a high Q factor (quality factor) due to a conductor loss of the microstrip line 12 even though the dielectric resonator 14 has a high Q factor.
Furthermore, in the conventional dielectric resonant device, the dielectric resonator 14, which is separately manufactured, is attached to the dielectric layer 10, so that a problem arises in that it is difficult to miniaturize the dielectric resonant device, and the manufacturing costs thereof are increased.